SortStack #981 — 2029-02-14

By speed · Order from slowest to fastest.

1. The creep of a mountain glacier 175320 mm/year

   Glaciers flow downhill under their own weight like very slow rivers of ice, grinding valleys as they go.

2. A crawling slug 30 m/h

   A slug glides on a ribbon of self-made slime, which lets it cross even a razor's edge unharmed.

3. A bottlenose dolphin 60 km/h

   Dolphins sleep with half their brain at a time, keeping one eye open to breathe and watch for danger.

4. A leaping blue marlin 108 km/h

   Marlins can change colour when excited, their stripes lighting up electric blue during a hunt.

5. The X-15 rocket plane 7.3K km/h

   The X-15 flew to the edge of space, and several of its pilots earned astronaut wings without leaving a runway.

6. A hypersonic missile 9.8K km/h

   Hypersonic weapons fly so fast and low they are extremely hard to track and intercept in time.

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